Description:
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When attempting to run builds of just chunkedhtml, etc, PhD cannot find the necessary parent classes. This can be fixed by either including all of the requisite classes from build.php, having the themes perform their necessary inclusions (be careful about register globals injections), or setting up some sort of autoload scheme.

Reproduce code:
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$ php build.php --theme chunkedhtml --docbook /path/to/phpdoc/.manual.xml

Expected result:
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Build proceeds as normal

Actual result:
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Fatal error: Class 'phpweb' not found in C:\Users\Edward\Webs\phd\themes\php\chu
nkedhtml.php on line 2